Yes, you have seen that title before. A couple of people brought it to my attention that my first entry did not answer this question fully, so I did a little editing. I've been pondering this for about a week and hope that I can give a satisfactory answer to the question, "Why do you write?"
In my original post I quoted some writers and their answers to this question. In once sense of the word, I believe that everyone who is called to write can give these answers. I will give you the quotes again and expand on them as a way to introduce this topic. If you are a writer (and even if you think you're not), I would appreciate reading your thoughts on why you write as well.
1. "My aim is to put down on paper what I see and what I feel in the best and simplest way."
-Ernest Hemingway
This is primarily my goal in writing. I have a unique perspective on life that no one else has (as do you). When I write, I want to share my perspective with others. Why on paper or on a blog screen? I'll deal with that more later, but I'm a detail oriented person. If I'm going to make a case for something (whether it's homeschooling or why God created the world in seven literal days), I want to have all the facts. Although I love details and facts, my brain does not always keep them readily available. When I sit down to write (or type), I can sort through the facts. I can research the things that aren't clear, and I can organize them in a neat pattern of thought.
2. "We do not write because we want to; we write because we have to." -W. Somerset Maugham
Writing is not something that I just decided one day I'd like to try like scrapbooking or skiing. (Actually, no, I haven't tried either of those things. If you have, I'll be glad to write a review on your experiences. 
) I did not begin to write back in kindergarten because I was naturally gifted. Yes, I am gifted on expressing my thoughts(no comments, Jerry!), but without filtering them through the writing process, they aren't usually understood like I had intended. I began writing the first time something touched my soul and my passions. My dad teases me about my impromptu song writing on the way to school as a kindergartener. I would literally sing about whatever was on my mind, and though it drove him crazy, he realized that the things in my heart were coming out of my mouth. Later on it was journals, notebooks, book reports (I loved those! Read a book and write about it, what could be better?), term papers, and blogs. The point is that those things could not be expressed any other way rather than recording the words that described the feelings I had (and have).
3. "The act of writing is the act of discovering what you believe." -David Hare
In the last few years, I've been faced with some changes in life, and some soul searching questions have surfaced many times. When something is really bothering me, I get out my Bible and study, then I start to write. By the time I'm done writing, I have a pretty good idea about what I believe about the subject at hand. Most of the time, I even write my prayers to God. That may sound heretical, but God hears and speaks to me just the same as when I speak audibly to Him. In my writings, I have a tangible record of my spiritual journey over the years.
Someone recently asked me what my purpose was in writing--what goal am I trying to accomplish and exactly what thoughts I feel a need to express. I can't give a simple answer to that any more than a pastor can say exactly what message he feels he needs to get to his parishioners. Yes, he could say he preaches the Bible, but there are so many wonderful facets to the Gospel and so many themes to expound upon within that Holy Book. Matthew 12:34 says, "...out of the abundance of the heart the mouth speaketh." My heart is full of the many things that the Lord shows me, and I feel compelled to share them.
I hope this post aptly answers the question, "Why Must I Write?" If not, you know what the comment box below is for!